From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
jpoimboe@redhat.com, mark.rutland@arm.com, dvyukov@google.com,
seanjc@google.com, pbonzini@redhat.com, mbenes@suse.cz
Subject: [RFC][PATCH 21/22] x86,word-at-a-time: Remove .fixup usage
Date: Thu, 04 Nov 2021 17:47:50 +0100 [thread overview]
Message-ID: <20211104165525.767986267@infradead.org> (raw)
In-Reply-To: 20211104164729.226550532@infradead.org
Push the load_unaligned_zeropad() exception into exception context by
adding a new extable type. This however requires we have both the
address and the output register. Since we can only have a single
register argument, use the same for both.
This also means the source can no longer use "m" constraint.
XXX: I'm not really happy with this patch
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/extable_fixup_types.h | 2 ++
arch/x86/include/asm/word-at-a-time.h | 27 +++++++--------------------
arch/x86/mm/extable.c | 17 +++++++++++++++++
3 files changed, 26 insertions(+), 20 deletions(-)
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -47,4 +47,6 @@
#define EX_TYPE_UACCESS_LEN4 (EX_TYPE_UACCESS_LEN | EX_TYPE_IMM(4))
#define EX_TYPE_UACCESS_LEN8 (EX_TYPE_UACCESS_LEN | EX_TYPE_IMM(8))
+#define EX_TYPE_LOAD_UNALIGNED 21 /* reg := (reg) */
+
#endif
--- a/arch/x86/include/asm/word-at-a-time.h
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -79,27 +79,14 @@ static inline unsigned long find_zero(un
*/
static inline unsigned long load_unaligned_zeropad(const void *addr)
{
- unsigned long ret, dummy;
+ unsigned long ret;
+
+ asm("1:\tmov (%0),%0\n"
+ "2:\n"
+ _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_LOAD_UNALIGNED, %0)
+ : "=&r" (ret)
+ : "0" ((unsigned long)addr));
- asm(
- "1:\tmov %2,%0\n"
- "2:\n"
- ".section .fixup,\"ax\"\n"
- "3:\t"
- "lea %2,%1\n\t"
- "and %3,%1\n\t"
- "mov (%1),%0\n\t"
- "leal %2,%%ecx\n\t"
- "andl %4,%%ecx\n\t"
- "shll $3,%%ecx\n\t"
- "shr %%cl,%0\n\t"
- "jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- :"=&r" (ret),"=&c" (dummy)
- :"m" (*(unsigned long *)addr),
- "i" (-sizeof(unsigned long)),
- "i" (sizeof(unsigned long)-1));
return ret;
}
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -170,6 +170,21 @@ static bool ex_handler_uaccess_len(const
return ex_handler_uaccess(fixup, regs, trapnr);
}
+static bool ex_handler_load_unaligned_zeropad(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int reg)
+{
+ unsigned long addr, offset, data;
+
+ addr = *pt_regs_nr(regs, reg);
+ offset = addr & (sizeof(unsigned long) - 1);
+ addr &= ~(sizeof(unsigned long) - 1);
+ data = *(unsigned long *)addr;
+ data >>= offset*8;
+ *pt_regs_nr(regs, reg) = data;
+
+ return ex_handler_default(fixup, regs);
+}
+
#define EX_TYPE_MASK 0x000000FF
#define EX_REG_MASK 0x00000F00
#define EX_FLAG_MASK 0x0000F000
@@ -251,6 +266,8 @@ int fixup_exception(struct pt_regs *regs
return ex_handler_kvm_fastop(e, regs);
case EX_TYPE_UACCESS_LEN:
return ex_handler_uaccess_len(e, regs, trapnr, reg, imm);
+ case EX_TYPE_LOAD_UNALIGNED:
+ return ex_handler_load_unaligned_zeropad(e, regs, reg);
}
BUG();
}
next prev parent reply other threads:[~2021-11-04 17:01 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 16:47 [RFC][PATCH 00/22] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 01/22] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-04 18:00 ` Borislav Petkov
2021-11-05 11:20 ` David Laight
2021-11-04 20:22 ` Josh Poimboeuf
2021-11-05 8:05 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 03/22] x86,copy_user_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 04/22] x86,copy_mc_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 05/22] x86,entry_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 06/22] x86,entry_32: " Peter Zijlstra
2021-11-04 20:39 ` Josh Poimboeuf
2021-11-05 7:43 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 07/22] x86,extable: Extend extable functionality Peter Zijlstra
2021-11-04 21:49 ` Josh Poimboeuf
2021-11-05 7:54 ` Peter Zijlstra
2021-11-05 10:16 ` Mark Rutland
2021-11-05 17:32 ` Sean Christopherson
2021-11-05 18:45 ` Peter Zijlstra
2021-11-05 19:17 ` Sean Christopherson
2021-11-05 19:32 ` Peter Zijlstra
2021-11-05 19:47 ` Sean Christopherson
2021-11-05 20:15 ` Peter Zijlstra
2021-11-05 20:26 ` Peter Zijlstra
2021-11-05 22:30 ` Sean Christopherson
2021-11-04 16:47 ` [RFC][PATCH 08/22] x86,msr: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 09/22] x86,futex: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 10/22] x86,uaccess: " Peter Zijlstra
2021-11-04 22:28 ` Josh Poimboeuf
2021-11-04 16:47 ` [RFC][PATCH 11/22] x86,xen: " Peter Zijlstra
2021-11-04 22:31 ` Josh Poimboeuf
2021-11-05 7:56 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 12/22] x86,fpu: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 13/22] x86,segment: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 14/22] x86,ftrace: " Peter Zijlstra
2021-11-04 22:35 ` Josh Poimboeuf
2021-11-05 7:57 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 15/22] x86,vmx: " Peter Zijlstra
2021-11-04 18:50 ` Paolo Bonzini
2021-11-05 18:17 ` Sean Christopherson
2021-11-05 18:52 ` Peter Zijlstra
2021-11-05 20:58 ` Peter Zijlstra
2021-11-05 22:29 ` Sean Christopherson
2021-11-06 7:05 ` Paolo Bonzini
2021-11-06 8:36 ` Peter Zijlstra
2021-11-07 19:13 ` Paolo Bonzini
2021-11-06 8:28 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 16/22] x86,checksum_32: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 17/22] x86,sgx: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 18/22] x86,kvm: " Peter Zijlstra
2021-11-04 18:50 ` Paolo Bonzini
2021-11-05 7:58 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 19/22] x86,usercopy_32: Simplify Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 20/22] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` Peter Zijlstra [this message]
2021-11-04 23:33 ` [RFC][PATCH 21/22] x86,word-at-a-time: " Josh Poimboeuf
2021-11-05 8:04 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 22/22] x86: Remove .fixup section Peter Zijlstra
2021-11-04 23:00 ` Josh Poimboeuf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211104165525.767986267@infradead.org \
--to=peterz@infradead.org \
--cc=dvyukov@google.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mbenes@suse.cz \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).